Though we have published buoyancy tables for the cylinders we distribute, the team at Silent Planet were often asked about weights and the trim of the various cylinders that we sold. Liisa and David Wallace teamed up with Richard Walker (GUE instructor) to undertake some tests that would have a little more validity than some you may come accross on the internet. For starters the water depth was far deeper than the length of the longest cylinder.
We tested the cylinders the we distribute in the UK that are manufactured by Luxfer and ECS and which may be used as stages or deco bottles.
This page has the photographic results for each of the cylinders we tested. If you view with Piclens there is text information regarding each picture including the buoyancy at each stage. Finally at the end of the page we have tabulated the results.
Initial setup shots from 23rd March 2009 where we took a range of cylinders and checked their buoyancy in fresh water. We tested each cylinder full, half full plus 15 bar and finally with 30 bar remaining. After each weight record we photographed the cylinder to see how it trimmed out.
The Team setting up!
3 litre 232 bar Ali cylnder
5 litre 232 bar Steel cylinder from Silent Planet
7 litre 200 bar Ali cylinder from Silent Planet
7 litre 232 bar Ali cylinder current from Sea and Sea
7 litre 232 bar Ali cylinder old version from Sea and Sea
7 litre 232 bar Steel cylinder from Silent Planet
10 litre 232 bar Steel Faber cylinder
12 litre 232 bar Steel Faber cylinder
12 litre 232 bar Steel cylinder from Silent Planet
40 cf 200 bar Ali from Silent Planet
80 cf 200 bar Ali from Silent Planet
| Cylinder weights in fresh water | ||||
| Bar | Bar | |||
| Full | 110 | 30 | Stamped weight | |
| Ali 3L | 2.10 | 1.72 | 0.96 | 4.36 |
| Ali 40cf | 1.53 | 1.00 | 0.38 | 6.90 |
| Ali 7L 232 (old Sea & Sea) | 2.00 | 1.12 | 0.20 | 8.70 |
| Ali 7L 232 (current Sea & Sea) | 2.38 | 1.82 | 1.08 | 9.98 |
| Ali 7L 200 bar | 1.78 | 1.15 | 0.34 | 8.82 |
| Ali 80cf | 2.00 | 1.00 | 0.10 | 14.30 |
| (positive) | ||||
| Steel 5L Eurocylinder | 3.90 | 3.26 | 2.70 | 7.16 |
| Steel 7L Eurocylinder | 4.16 | 3.30 | 2.60 | 9.08 |
| Steel 10L Faber | 4.10 | 3.20 | 2.04 | 10.90 |
| Steel 12L Faber | 4.60 | 3.40 | 2.42 | 13.80 |
| Steel 12L Eurocylinder | 5.45 | 3.90 | 27.00 | 14.10 |
Below are some calculated tables.
The first represents the additional lift that the cylinders will have when used in salt water. The numbers given represent the additional buoyancy or to put it another way, how much lead you would have to add to the cylinder to get back to same buoyancy experienced in the test.
The remaining tables depict the change in buoyancy you would experience with various gasses in the cylinder in comparison to the test result. Where a negative number is shown this represents additional buoyancy or to put it another way, how much lead you would have to add to the cylinder to get back to same buoyancy experienced in the test.
| Additional Lift in Seawater | Kg | ||
| Ali 3L | 0.09 | ||
| Ali 40cf | 0.16 | ||
| Ali 7L 232 (old Sea & Sea) | 0.19 | ||
| Ali 7L 232 (current Sea & Sea) | 0.20 | ||
| Ali 7L 207 bar | 0.19 | ||
| Ali 80cf | 0.31 | ||
| Steel 5L Eurocylinder | 0.18 | ||
| Steel 7L Eurocylinder | 0.25 | ||
| Steel 10L Faber | 0.34 | ||
| Steel 12L Faber | 0.42 | ||
| Steel 12L Eurocylinder | 0.41 | ||
| Additional buoyancy or negitive buoyancy with different gasses | |||
| Difference with 32% | Kg | Kg | Kg |
| Ali 3L | 0.014 | 0.006 | 0.002 |
| Ali 40cf | 0.023 | 0.012 | 0.003 |
| Ali 7L 232 (old Sea & Sea) | 0.032 | 0.015 | 0.004 |
| Ali 7L 232 (current Sea & Sea) | 0.032 | 0.015 | 0.004 |
| Ali 7L 207 bar | 0.027 | 0.015 | 0.004 |
| Ali 80cf | 0.045 | 0.024 | 0.007 |
| Steel 5L Eurocylinder | 0.023 | 0.011 | 0.003 |
| Steel 7L Eurocylinder | 0.032 | 0.015 | 0.004 |
| Steel 10L Faber | 0.046 | 0.022 | 0.006 |
| Steel 12L Faber | 0.057 | 0.027 | 0.007 |
| Steel 12L Eurocylinder | 0.055 | 0.026 | 0.007 |
| Differece with 21/35 | Kg | Kg | Kg |
| Ali 3L | -0.261 | -0.124 | -0.034 |
| Ali 40cf | -0.443 | -0.235 | -0.064 |
| Ali 7L 232 (old Sea & Sea) | -0.609 | -0.289 | -0.079 |
| Ali 7L 232 (current Sea & Sea) | -0.609 | -0.289 | -0.079 |
| Ali 7L 207 bar | -0.525 | -0.289 | -0.079 |
| Ali 80cf | -0.862 | -0.458 | -0.125 |
| Steel 5L Eurocylinder | -0.435 | -0.206 | -0.056 |
| Steel 7L Eurocylinder | -0.609 | -0.289 | -0.079 |
| Steel 10L Faber | -0.870 | -0.413 | -0.113 |
| Steel 12L Faber | -1.088 | -0.516 | -0.141 |
| Steel 12L Eurocylinder | -1.044 | -0.495 | -0.135 |
| Difference with 18/45 | Kg | Kg | Kg |
| Ali 3L | -0.339 | -0.161 | -0.044 |
| Ali 40cf | -0.575 | -0.306 | -0.083 |
| Ali 7L 232 (old Sea & Sea) | -0.792 | -0.376 | -0.102 |
| Ali 7L 232 (current Sea & Sea) | -0.792 | -0.376 | -0.102 |
| Ali 7L 207 bar | -0.683 | -0.376 | -0.102 |
| Ali 80cf | -1.121 | -0.595 | -0.162 |
| Steel 5L Eurocylinder | -0.566 | -0.268 | -0.073 |
| Steel 7L Eurocylinder | -0.792 | -0.376 | -0.102 |
| Steel 10L Faber | -1.131 | -0.536 | -0.146 |
| Steel 12L Faber | -1.414 | -0.671 | -0.183 |
| Steel 12L Eurocylinder | -1.358 | -0.644 | -0.176 |
| Difference with 15/55 | Kg | Kg | Kg |
| Ali 3L | -0.418 | -0.198 | -0.054 |
| Ali 40cf | -0.708 | -0.376 | -0.103 |
| Ali 7L 232 (old Sea & Sea) | -0.975 | -0.462 | -0.126 |
| Ali 7L 232 (current Sea & Sea) | -0.975 | -0.462 | -0.126 |
| Ali 7L 207 bar | -0.840 | -0.462 | -0.126 |
| Ali 80cf | -1.379 | -0.733 | -0.200 |
| Steel 5L Eurocylinder | -0.696 | -0.330 | -0.090 |
| Steel 7L Eurocylinder | -0.975 | -0.462 | -0.126 |
| Steel 10L Faber | -1.393 | -0.660 | -0.180 |
| Steel 12L Faber | -1.741 | -0.825 | -0.225 |
| Steel 12L Eurocylinder | -1.671 | -0.792 | -0.216 |
| Difference with 50% | Kg | Kg | Kg |
| Ali 3L | 0.036 | 0.017 | 0.005 |
| Ali 40cf | 0.061 | 0.032 | 0.009 |
| Ali 7L 232 (old Sea & Sea) | 0.084 | 0.040 | 0.011 |
| Ali 7L 232 (current Sea & Sea) | 0.084 | 0.040 | 0.011 |
| Ali 7L 207 bar | 0.072 | 0.040 | 0.011 |
| Ali 80cf | 0.119 | 0.063 | 0.017 |
| Steel 5L Eurocylinder | 0.060 | 0.028 | 0.008 |
| Steel 7L Eurocylinder | 0.084 | 0.040 | 0.011 |
| Steel 10L Faber | 0.120 | 0.057 | 0.016 |
| Steel 12L Faber | 0.150 | 0.071 | 0.019 |
| Steel 12L Eurocylinder | 0.144 | 0.068 | 0.019 |
| Difference with 100% | Kg | Kg | Kg |
| Ali 3L | 0.098 | 0.047 | 0.013 |
| Ali 40cf | 0.166 | 0.088 | 0.024 |
| Ali 7L 232 (old Sea & Sea) | 0.229 | 0.109 | 0.030 |
| Ali 7L 232 (current Sea & Sea) | 0.229 | 0.109 | 0.030 |
| Ali 7L 207 bar | 0.197 | 0.109 | 0.030 |
| Ali 80cf | 0.324 | 0.172 | 0.047 |
| Steel 5L Eurocylinder | 0.163 | 0.078 | 0.021 |
| Steel 7L Eurocylinder | 0.229 | 0.109 | 0.030 |
| Steel 10L Faber | 0.327 | 0.155 | 0.042 |
| Steel 12L Faber | 0.409 | 0.194 | 0.053 |
| Steel 12L Eurocylinder | 0.392 | 0.186 | 0.051 |